feat(tailscalectl): add periodic status polling and reactive state

Add Timer (5s interval) that runs tailscale status --json, parsing
BackendState, Self.TailscaleIPs[0], and CurrentExitNode.HostName into
isConnected, tailscaleIP, and currentExitNode properties. Parse errors
surface via ToastService.showError. Initial check runs on load.

Closes #4

tailscalectl/TailscaleWidget.qml

@@ -9,6 +9,17 @@ PluginComponent {
     id: root
 
     property bool isConnected: false
+    property string tailscaleIP: ""
+    property string currentExitNode: ""
+
+    Timer {
+        interval: 5000
+        running: true
+        repeat: true
+        onTriggered: statusCheck.running = true
+    }
+
+    Component.onCompleted: statusCheck.running = true
 
     Process {
         id: toggleProcess
@@ -28,8 +39,13 @@ PluginComponent {
                 try {
                     const data = JSON.parse(this.text)
                     root.isConnected = data.BackendState === "Running"
+                    root.tailscaleIP = (data.Self?.TailscaleIPs?.[0]) || ""
+                    root.currentExitNode = data.CurrentExitNode?.HostName || ""
                 } catch (e) {
                     root.isConnected = false
+                    root.tailscaleIP = ""
+                    root.currentExitNode = ""
+                    ToastService.showError("tailscalectl", "Failed to parse Tailscale status")
                 }
             }
         }
@@ -37,6 +53,8 @@ PluginComponent {
         onExited: (code, status) => {
             if (code !== 0) {
                 root.isConnected = false
+                root.tailscaleIP = ""
+                root.currentExitNode = ""
             }
         }
     }